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WATLOW Series 988 User’s Manual 8.21
General Software Features, Chapter 8
General Software
Sample Applications
A Series 988 is being used to control the temperature of a heat-treat oven.
The temperature of the process must be recorded on a chart recorder. The
oven temperature range stays between 600° and 900° F. The chart
recorder requires a 4-20mA signal.
In the Output Menu [OtPt] set analog output [Aout] to [Prc1] to tag the
input 1 process value as the parameter to be retransmitted. Set retransmit
low limit [`ArL] to 600 to set the low range for the retransmit signal to
600. Set retransmit high limit [`ArH] to 900 to set the high range for the
retransmit signal to 900. Set retransmit calibrate offset [ACAL] to 0,
assuming there is no calibration offset required.
The retransmit output will be 4mA until the oven temperature is greater
than 600 degrees F, at which point the signal will increase with tempera-
ture to 20mA at 900° F and will not exceed 20mA.
TL
W
W
A
PROCESS
L1 L2 L3 L4
DEV
% OUT
DISPLAY
MODE
AUTO
MAN
SERIES 988
input 1 output 1
output 3
limit
limit
sensor
heaters
temperature
sensor
Chart
Recorder
Heat-treat Oven
Figure 8.21 -
Heat-treat oven with
retransmit.
C8.wc 5/14/1999 8:55 AM Page 8.21